The present invention relates to closed-loop robotic material processing operations such as cutting, welding, drilling, heat treatment and the like employing laser energy.
A variety of industrial robots have been developed which employ closed-loop feedback for precise control of material processing operations. An important example is electric arc welding by robotic manipulation of a welding head along a seam. To this end, various seam tracking systems have been developed which, in general, project a striped light pattern accross the seam and at the same time view the pattern to determine the position of the seam. Seam tracking and vision have been integrated with tungsten-inert-gas (TIG) and metal-inert-gas (MIG) welding processes. Examples of welding torches integrated with seam tracking are disclosed, for example, in commonly-assigned Corby, Jr. U.S. Pat. No. 4,450,339 and Nachev et al. U.S. Pat. No. 4,417,127. Other examples of robotic control of welding processes are disclosed in Kremers et al. U.S. Pat. Nos. 4,412,121, 4,410,787 and Westby U.S. Pat. No. 3,976,382.
In addition to conventional welding processes, material processing lasers have also been integrated to industrial robots employing fiber optic cables to transmit laser energy to a robotic tool for various material processing operations, such as the above-noted cutting, welding, drilling, and heat treatment. In such systems, laser energy in the near infrared and visible spectrum is transmitted through an optical fiber at power levels sufficient for material processing. Laser material processing has a number of advantages over arc welding, such as lower (but more highly focused) heat input, less distortion, and a higher quality weld.
As one example, the system disclosed in Sakuragi et al. U.S. Pat. No. 4,443,684 includes a C0.sub.2 laser (generating energy at a wavelength of 10.6 micrometers) coupled through an optical fiber to an output end carried by the carriage of an XY plotter adapted for the purpose. Workpieces to be thermally transformed are placed on the normal working surface of the plotter, and the carriage then travels thereover. In order to measure temperatures of workpieces to be machined, the system of of U.S. Pat. No. 4,443,684 includes another optical fiber for transmitting infrared rays from the workpiece to a detector.
Although robotic control is not disclosed, heat treatment by laser beam transmitted through an optical fiber is disclosed in Japanese Patent Document (KOKAI) No. S.57 (1982) - 92133. In the system of this Japanese Patent Document, 1.06 micrometer laser energy from a YAG laser is coupled through a glass fiber to an output element for heat treatment of small teeth. It is mentioned that the heat treatment of the workpiece might be observed and recorded through a television monitor by including an optic system such as a half-mirror in the output element.
Further examples of laser material processing through an optical fiber are disclosed in commonly-assigned U.S. patent application Ser. No. 450,951, filed Dec. 20, 1982 by M. G. Jones and G. Georgalas entitled "Laser Material Processing Through a Fiber Optic", and in commonly-assigned Application Ser. No. 608,042, filed May 7, 1984, by M. G. Jones and D. C. Richardson, entitled "Industrial Hand Held Laser Tool and Laser System".
Yet another example is disclosed in commonly-assigned U.S. patent application Ser. No. 649,125 filed Oct. 9, 1984 by M. G. Jones, entitled "High Power Laser Energy Delivery System" which discloses the use of an Nd:YAG total-internal-reflection, face-pumped laser (TIR-FPL) coupled to an optical fiber having a diameter less than 600 micrometers for transmitting material processing laser energy to a workpiece.